Interpretive Summary: Stable flies, Stomoxys calcitrans (L.), are one of the most serious livestock pests that feed mainly on cattle and cause significant economic loss in the cattle industry. Standard stable fly control involving insecticides and sanitation usually is costly with only limited effectiveness. The present study reports 1) the discovery of catnip oil and its active ingredient compounds, nepetalactones, as an effective repellent against stable fly biting and oviposition inhibition; and 2) development of formulations for field applications.

Technical Abstract:
We have discovered that catnip oil reduced the feeding of stable flies by more than 96% in the laboratory bioassays, when compared with other sesquiterpene-rich amyris and sandalwood oils. Catnip oil further demonstrated with a strong repellency against stable flies, relative to other newly identified biting insect repellents, including isolongifolenone, 2-methylpiperidinyl-3-cyclohexen-1-carboxamide and (1S,2'S)-2-methylpiperidinyl-3-cyclohexen-1-carboxamide. The repellency against stable flies from the most commonly used insect repellent, DEET, was relatively low. In field trials, two formulations of catnip oil provided > 95% protection while tested on cattle, with an effective time up to 6 hours. Catnip oil also acted as a strong oviposition repellent, and it reduced gravid stable fly oviposition with a 98% inhibition-rate.